1.
On Sept. 3, Michael Fulmer left a sinker up in the zone, and Daniel Palkalined it back up the middle. The ball hit Fulmer in the shin and was redirected to the first baseman Niko Goodrum. As Fulmer tumbled to the ground, Goodrum picked the ball up and stepped on first base for the out. Fulmer stood up and circled back to the mound. The Tigers' trainer came out to check on him, and without asking Fulmer to throw a practice pitch, manager Ron Gardenhire replaced him. Fulmer walked to the dugout without a limp.

2.
On Sept. 8, 2000, the Yankees' Ryan Thompson lined a ball back at Red Sox pitcher Bryce Florie. It hit Florie in the face. Florie fell to the ground, then sat up with blood streaming from his nose and mouth and around his eyes.

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After the game, everybody involved struggled to the find the words to convey the violence. Some tried to describe the ball: "A wicked liner," said the Boston Herald; it was "smoked," "smashed" and "smacked," according to three other accounts. Some tried to describe the sound: "It sounded like someone stepping on glass," Thompson said; it sounded "like someone clapped their hands," said crew chief Bruce Froemming. Red Sox pitching coach Joe Kerrigan described it as a sequence, a series of events too sudden for a human time scale: "It was almost simultaneous, the crack of the bat and ball hitting flesh." The AP described it with diagnostic directness: "His retina was damaged but not detached."

Florie himself, after he recovered, recalled being on the mound and thinking of a number: "OK, this ball hit me going 100 mph in my head." But that number didn't exist at the time as anything but an abstraction. In 2000, there was no measurement of the speed of a ball off a bat. One hundred miles per hour was simply the highest number most of us could think of in relation to a moving baseball. Any number higher would have been meaningless.

If it had happened 18 years later, Statcast would have recorded it, and the real number certainly would have been higher than 100 mph, and it would have been in every article about Florie's injury, surgery and recovery. When the Tigers' Jordan Zimmermann was hit in the jaw by a line drive this past April -- and somehow escaped serious injury -- the speed of the ball was in the 17th paragraph of the game story: "105.6 mph, according to Statcast™." Fulmer retweeted Zimmermann that day:

The ball that would hit Fulmer five months later was 115.6 mph. It was the 83rd-hardest hit baseball of the 2018 season. We searched Statcast for all the comebackers that had been turned into outs, and the one Palka hit to Fulmer -- thanks to a well-directed ricochet -- was at the top of the column. "I tell you, he's a special guy," the Tigers broadcast gushed when Fulmer got back up, after they'd relayed the exit velocity.

"Yeah, that's what my wife said, 116 [mph]. That's the first thing she said to me," Fulmer said, according to one game story. "She asked me if I was all right. I said yeah. She goes, 'It was 116 miles off the bat,' and I said, 'Well, [I won't] throw it there again.'"

3.
On May 1, Edwin Encarnacion lined a ball back at Jake Diekman, who has a big follow-through that carries him almost 180 degrees. The liner hit Diekman in the back, and, Diekman ceased to move like a human. He first straightened comically upright, a string pulled taut. Then, with his shoulders pulled way back and his arms akimbo, his torso suddenly sprung forward, and he bucked forward like a chicken. His legs started chugging, but his upper body wasn't really alive to it yet, and he staggered down to a knee and then all fours. Along the way, his arms had started to wiggle like loose shoelaces, and his glove tumbled off and away. And then, just as quickly, he was up, walking around, giving a thumbs-up to his teammates. It looked like he had been tased. The ball had been hit 112 mph.

One of the nice things about Statcast is its precision. It can tell us the ball that hit Michael Fulmer was traveling faster than the ball that had hit Diekman. Sometimes, that distinction is useful. But another nice thing is it has shown us the range of baseball physics, confirming our intuitions -- comebackers come back really fast! -- and giving us a more accurate scale. Knowing the Encarnacion ball was hit 112 mph and the Palka ball was hit 116 mph, tells us something about both of them we could only speculate on back in the days of "this ball hit me going 100 mph."

It's an extraordinary number, 115.6. (And so is 112!) A ball going 115.6 mph travels 170 feet per second (though, thanks to air resistance, it slows as it goes). Giancarlo Stanton hit a ball 115.8 mph in 2016, and it landed 504 feet away from home plate. Imagine this home run,

and then imagine standing in its path, just 55 feet away from contact, a little off balance from your follow-through, with your glove on the other side of your body, trying to dodge it -- or, even, catch it. That's the second half of pitching.

A baseball hit 115.6 mph at the pitcher carries about 50 percent more kinetic energy than a pitch thrown 95 mph at the batter. It travels the 55 feet out in about 80 percent of the time that it traveled the 55 feet in. It goes very nearly as fast as the BB gun in "A Christmas Story" could shoot.

The ball that hit Fulmer connected with his right shin at almost exactly the same time that his right foot landed on the ground from his pitching motion. This is where the ball was when his foot landed, that little white speck (which we circled in red for you):

So when Fulmer had merely finished his pitching, had merely put both feet on the earth and regained a very basic bipedal balance, the ball was perhaps three feet away from him, and traveling three feet every 1/50th of a second. He had no shot. He still tried to leap out of the way. It was the leap -- way, way, way too late -- that led to his tumble to the ground.

His body started fleeing after the ball had already hit him.

4.
All of this puts into perspective how scary pitching is. It also puts into perspective how incredible our brains are.

A fastball going 100 mph "hits a speed that is right at the limit of the fastest a human eye can track in a moment," a neuroscientist told the Seattle Times last year. A line drive going 115.6 mph is much faster than that! The amount of time the ball spent traveling from home to Fulmer is roughly the time it takes for our brains to process grammar. It's impossibly fast, is what I'm saying.

And yet, our brains do the impossible. Look at the transformation that takes place in these fans who were watching Palka face Fulmer -- particularly the woman and the girl in the front row, and the woman in the white shirt in the second row:

Both of those pictures came after Palka's contact but before the ball hit Fulmer. They weren't reacting to Fulmer falling, or being hurt, but to the ball's path at Fulmer. In the space of roughly 0.3 seconds, three fans had identified the danger to another human being, and they already had emotions and physical reactions.

"Descriptions are sparse because pitchers unlucky enough to be struck all say the same thing -- it's over before it begins," said the LA Times in a 1998 article about comebackers. I first read that sentence as saying a comebacker happens so fast pitchers barely perceive it. I think I read it wrong. It's actually saying there's just not much to describe: A comebacker is a violent sequence but a very simple one, a short line separating two nearby points. "I saw it," Billy Wagner said of the comebacker that got him in 1998. "I was just too slow."

But sometimes they're not too slow. On Sept. 25, Aaron Judge lined a ball back at Jacob Faria. A 109 mph line drive from Aaron Judge is no harder than a 109 mph line drive from anyone else, but as anybody who has ever been fooled by the "ton of feathers or ton of bricks" riddle knows, it doesn't seem that way. This line drive was not at Faria's shin but his face. His glove was down by his hip at the end of his follow-through, but in the 0.3 seconds it took for the ball to get back to him he pulled the glove up, in front of his face, and caught it. As the ball came within feet of Faria's face (we circled it in red again for you), nobody else on the field had reacted except Faria, who had to:

He caught it, somehow, the fastest line drive caught by a pitcher this season. It happened so fast that Judge, after the ball was caught, took his first running steps toward first base.

Faria looked to check the runner on first, then to check the runner on second -- there was no runner on second. These plays happen so fast you start to notice, if you watch a bunch of them in one afternoon, that people involved get disoriented by them. They look to the wrong base, they forget to run, they misremember things after the fact. Fulmer "literally refused to go to the ground," a Tigers broadcaster said after the Palka play, which just wasn't true at all. One of the game's broadcast crews thought they saw the ball bounce before it hit Fulmer (it didn't), while another thought the ball hit Fulmer in the thigh (it didn't). The speed of the play is within the range of our reactions -- see the girl in the front row -- but not our comprehension.

"Experience isn't what happens to you," the legendary sports psychologist Harvey Dorfman said about comebackers. "It's how you perceive what happens to you."

5.
On Aug. 11, Jose Abreu lined a ball back at Trevor Bauer. Bauer tried to spin away from it, but it was hit way too fast. The ball hit him on the back of his ankle, broke his right fibula and knocked him out of action for the next six weeks. Bauer would return in time for the playoffs, but as a reliever, not a starter. The injury might well have cost him the Cy Young Award -- and might well have cost the Indians any realistic chance at advancing in the playoffs.

Statcast tells us the ball was hit 92 mph. By the standards of comebackers -- and compared to the bullet hit at Fulmer -- it was practically a blooper. It did immense damage.

If Statcast answers our questions with more precision, it is still up to us to ask the questions. A ball doesn't need to travel 116 mph -- or even 100 mph -- to hurt a human body, to end a career. It also doesn't need to travel nearly that fast to be unavoidable. Some comebackers hit the pitcher because they're going too fast to avoid, but others because they're hit in the pitcher's blind spot or because they're hit at a part of the body -- especially the lower legs -- too far from the pitcher's fielding hand. Depth perception is so limited at that range a pitcher can see the ball coming but not really calculate how quickly it's coming. Further, if the ball does hit the pitcher, the fragile parts of the body and the strong parts are often right next to each other.

Amir Garrett had to leave a game on June 27 after he was hit by a comebacker -- at 96 mph. Carlos Carrasco was hit by a 100 mph comebacker and left. Vince Velasquez was hit by a 96 mph ball and looked like he was in far more pain than Fulmer was. It tells us something about the fear pitchers must live with to know some baseballs come back at them at 115.6 mph. But it's not just the top of a column sort that tells us about this danger. It's the whole sport, hundreds and hundreds of these balls, every one of them a terror. The difference between 92 mph and 115.6 mph is often just the difference between a piano landing on you and two pianos landing on you.

And sometimes the two pianos miraculously bounce off. Fulmer would make his next start.

"Everything checks out," he told reporters after the Palka game, his leg bandaged up. "It's just a big welt. I'm just gonna keep doing treatment on it and stuff. It's been worse before."